Bone anchoring device

Patent metadata

Field	Value
Publication number	US-2016000470-A1
Application number	US-201514738537-A
Country	US
Kind code	A1
Filing date	Jun 12, 2015
Priority date	Jan 30, 2012
Publication date	Jan 7, 2016
Grant date	—

Abstract

A polyaxial bone anchoring device includes a bone anchoring element having a head and a shaft, a receiving part having a head receiving portion, a rod receiving portion, and a bore having a bore axis, and a pressure member movable in the bore and having a first surface for engaging the head, wherein the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and wherein the pressure member is configured to engage the receiving part to generate a holding force for holding the pressure member at the first position without a positive lock, and wherein the pressure member is movable in and out of the first position by applying an axial force on the pressure member greater than the holding force.

First claim

1 . A polyaxial bone anchoring device comprising:
a bone anchoring element having a head and a shaft for anchoring to a bone; a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis; and a pressure member movable in the bore and comprising a first surface for engaging the head, a second surface for engaging a rod, and an outer surface with a first portion having a first width and a second portion comprising at least one projection that extends radially outwards from other parts of the pressure member to define a width of the pressure member that is greater than the first width; wherein when the bone anchoring element and the pressure member are in the receiving part, the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and to a second position different from the first position where the head is locked relative to the receiving part; and wherein the first portion of the outer surface of the pressure member is configured to engage the inner wall of the receiving part without a positive lock to generate a holding force for holding the pressure member at the first position while the second portion of the outer surface of the pressure member is spaced apart from the inner wall, and wherein the pressure member is movable out of the first position by applying an axial force on the pressure member that is greater than the holding force.

2 . The poyaxial bone anchoring device of claim 1 , wherein the pressure element is held at the first position by a radial force that generates friction between the pressure member and at least a portion of the receiving part.

3 . The polyaxial bone anchoring device of claim 1 , wherein the pressure member is configured to form an interference fit with the receiving part in the first position.

4 . The bone anchoring device of claim 1 , wherein at least a portion of a surface defining the bore is roughened, fluted, grooved or ridged.

5 . The bone anchoring device of claim 1 , wherein at least a portion of the outer surface of the pressure member is roughened, fluted, grooved or ridged.

6 . The bone anchoring device of claim 1 , wherein the second portion of the outer surface of the pressure member comprises two projections configured to latch into annular grooves in the receiving part when the pressure member is in the receiving part.

7 . The bone anchoring device of claim 1 , wherein the pressure member is substantially cylindrical.

8 . The bone anchoring device of claim 1 , wherein the pressure member has a first end and a second end, and a recess at the second end with a spherical-segment shape corresponding to a spherical-segment shaped surface portion of the head of the bone anchoring element.

9 . The bone anchoring device of claim 1 , further comprising a sleeve-like insert piece configured to be positioned around a spherical-segment shaped portion of the head, wherein the insert piece is configured to pivot in the accommodation space of the receiving part, and wherein when the insert piece is seated in the receiving part and has a central axis coaxial with the bore axis, a lower edge of the insert piece extends out of a lower opening of the receiving part.

10 . The polyaxial bone anchoring device of claim 1 , wherein the receiving part comprises a set screw, and wherein the pressure member is held in the first position when the set screw extends into the bore and is in frictional contact with the outer surface of the pressure member.

11 . The polyaxial bone anchoring device of claim 1 , wherein the pressure member is held in the first position by crimping a portion of either the pressure member or the receiving part.

12 . A method of manufacturing a polyaxial bone anchoring device comprising a bone anchoring element having a head and a shaft for anchoring to a bone, a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis, and a pressure member comprising a first surface for engaging the head, a second surface for engaging a rod, and an outer surface with a first portion having a first width and a second portion comprising at least one projection that extends radially outwards from other parts of the pressure member to define a width of the pressure member that is greater than the first width, wherein when the bone anchoring element and the pressure member are in the receiving part, the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and to a second position different from the first position where the head is locked relative to the receiving part, the method comprising:
inserting the head of the bone anchoring element in the receiving part; inserting the pressure member in the receiving part applying an axial force on the pressure member to move the pressure member to the first position to generate the preload on the head of the bone anchoring element, wherein the first portion of the outer surface of the pressure member engages the inner wall of the receiving part without a positive lock to generate a holding force for holding the pressure member at the first position while the second portion of the outer surface of the pressure member is spaced apart from the inner wall, and wherein the pressure member is movable out of the first position by applying an axial force on the pressure member that is greater than the holding force.

13 . The method of claim 12 , wherein the holding force is a radially acting force.

14 . The method of claim 13 , wherein the radially acting force is generated by an interference fit between the pressure member and the receiving part.

15 . The method of claim 13 , wherein the receiving part comprises a set screw, and wherein the radially acting force is generated by screwing the set screw into a through bore in the receiving part to exert pressure on the pressure member.

16 . The method of claim 13 , further comprising crimping one of the receiving part or the pressure member, wherein the radially acting force is generated by a deformed portion formed by the crimping exerting pressure between the pressure member and the receiving part.

17 . A method for coupling a rod to a bone via a polyaxial bone anchoring device comprising a bone anchoring element having a head and a shaft for anchoring to a bone, a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis, a pressure member movable in the bore and comprising a first surface for engaging the head, a second surface for engaging a rod, and an outer surface with a first portion having a first width and a second portion comprising at least one projection that extends radially ou

Assignees

• Biedermann Technologies Gmbh

Inventors

• Matthis Wilfried
• Meer Martin
• Biedermann Lutz

Classifications

• F04C2270/041

  Controlled or regulated · CPC title

• A61B17/8605

  Heads, i.e. proximal ends projecting from bone · CPC title

• A61B17/7035 Primary

  Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other · CPC title

• A61B17/7082

  for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws · CPC title

• A61B17/7049

  Connectors, not bearing on the vertebrae, for linking longitudinal elements together (A61B17/7055, A61B17/7053, A61B17/7019 take precedence) · CPC title